Non-intrusive flow indicator

ABSTRACT

Perforating devices, temporary dissolvable plugs, and dissolvable indicator devices for downhole tools all having at least one tracer are disclosed. Upon detonation of the perforating charge, dissolution of the temporary plug, or actuation of a downhole tool, the tracer is released and carried to the surface as an indictor to the operators of the well that the perforating charge detonated, the temporary plug dissolved, or the downhole tool actuated.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/839,880, filed Aug. 24, 2006.

BACKGROUND

1. Field of Invention

The invention is directed to downhole devices having tracers formonitoring and detecting flow contribution in oil and gas wells and forindicating that such devices have been activated or actuated and, inparticular, to perforating charges and dissolvable plugs containingtracers for monitoring and detecting flow contribution.

2. Description of Art

Perforating a well involves a special gun that shoots several relativelysmall holes in the casing. The holes are formed in the side of thecasing opposite the producing zone. These communication tunnels orperforations pierce the casing or liner and the cement around the casingor liner. The perforations go through the casing and the cement and ashort distance into the producing well formation. Well formationsfluids, which include oil, water, and gas, flow through theseperforations and into the well.

The most common perforating gun uses shaped charges, similar to thoseused in armor-piercing shells. A high-speed, high-pressure jetpenetrates the steel casing, the cement and the formation next to thecement. Other perforating methods include bullet perforating, abrasivejetting or high-pressure fluid jetting.

The characteristics and placement of the communication paths(perforations) can have significant influence on the productivity of thewell. Therefore, a robust design and execution process should befollowed to ensure efficient creation of the appropriate number, sizeand orientation of perforations. A perforating gun assembly with theappropriate configuration of shaped explosive charges and the means toverify or correlate the correct perforating depth can be deployed onwireline, tubing or coiled tubing.

Despite advances in perforation methods and devices, currently running asecond tool string to log the well is how operators of a well determinewhether new hydrocarbons, e.g., oil and gas, are entering the wellborethrough the perforations. Running a logging string after the perforatingstring increases the costs, and time, associated with recovery ofhydrocarbons. Therefore, it is desirable to have releasable indicatormaterial as part of the perforating apparatus that can indicate tooperators at the surface of the well that new hydrocarbons are beingrecovered from the formation.

Additionally, there are a number of procedures and applications thatinvolve the formation of a temporary seal or plug devices within thewellbore for other steps or processes to be performed, where the seal orplug devices must be later removed. Often such seal or plug devices areprovided to temporarily inhibit or block a flow pathway or the movementof fluids or other materials, such as flowable particulates, in aparticular direction for a short period of time, when later movement orflow is desirable.

A variety of applications and procedures where temporary coatings orplug devices are employed are involved in the recovery of hydrocarbonsfrom subterranean well formations where operations must be conducted atremote locations, namely deep within the earth, where equipment andmaterials can only be manipulated at a distance. One particular suchoperation concerns perforating and/or well completion operationsincorporating filter cakes and the like as temporary coatings.

In the perforating context, the communication paths of the perforationscan be temporarily blocked, filled or plugged while other operations areconducted that would cause problems if the perforations were left open.Such problems include, but are not necessarily limited to, undesirableleak-off of the working fluid into the well formation, and possibledamage to the well formation. Upon completion of the other operations,the temporary plug, filter cake, and coating devices, dissolve, ordegrade or disintegrate, so that hydrocarbon flow from the formation canresume. As with the perforating apparatus, it is desirable to havereleasable indicator materials as part of the temporary plugs, filtercakes, and coatings that can indicate to operators at the surface of thewell that hydrocarbon flow from the formation through the previouslyplugged perforations has resumed.

Accordingly, prior to the development of the present invention, therehas been no perforating devices, temporary plugs, or methods forindicating hydrocarbon flow that: provide an indication to operators atthe surface of a well that specific perforating charges have detonated;provide an indication to operators at the surface of the well as towhich perforations are contributing to flow; provide an indication tooperators at the surface of a well that a temporary plug has beenremoved; provide an indication to operators at the surface of the wellthat new hydrocarbons are being recovered from the formation; and/orprovide an indication to operators at the surface of the well thathydrocarbon flow from the formation through the previously pluggedperforations has resumed.

SUMMARY OF INVENTION

Broadly, the invention is directed to downhole devices, having at leastreleasable indicator material, such as a tracer, to indicate that afluid flow path has been formed in a wall of a wellbore. In oneparticular embodiment, the downhole devices are perforating chargeshaving at least one tracer that is placed in contact with theperforation formed by, or that is otherwise released by, the detonationof the perforating charge. In the event that the perforation is formedin a hydrocarbon production zone, the hydrocarbon flowing from theperforation carries the tracer to the surface of the well where it isdetected. Detection of such tracers by an operator at the surface of thewell indicates to the operator that the perforation formed by theperforating device successfully provided hydrocarbon flow from thehydrocarbon reservoir, or formation surrounding the well. Alternatively,the tracers could be carried to the surface by some other fluid, e.g.,drilling fluid, to indicate that the perforating charge properlydetonated, regardless of whether hydrocarbon flows from the formationthrough the perforation formed by the perforating charge.

In another aspect, the downhole device is directed to temporary plugsthat are disposed in the casing of oil and gas wells. These plugsinclude a tracer that, when released indicates that the casing is nolonger plugged. Preferably, the temporary plugs are formed from adissolvable material. As with the perforating charge, the tracer couldbe carried to the surface by hydrocarbon flowing from the well formationor by drilling fluid.

In still another aspect, the invention is directed to the use of tracersin downhole tools to indicate that the downhole tool has actuated, e.g.,set. Like the temporary plugs, a dissolvable material can comprise thereleasable indicator material, e.g., tracers. Upon dissolution, forexample, due to the tool actuating and drilling fluid coming intocontact with the dissolvable material, the tracer is released andcarried to the surface of the well for detection by the operator.

In one embodiment, a device for forming a fluid flow path in a wall of awellbore is disclosed. The device comprises a releasable indicatormaterial, the releasable fluid flow path indicator material beingreleasable from the device to indicate formation of a fluid flow path ina wall of a wellbore.

A further feature of the device is that the device may be a perforatingcharge having an explosive material and the releasable fluid flow pathindicator material is disposed within the explosive material. Anotherfeature of the device is that the device may be a perforating chargehaving an explosive material and a protective layer disposed over theexplosive material, and protective layer comprising the releasable fluidflow path indicator material. An additional feature of the device isthat the device may be a temporary plug disposed within an opening inthe wall of the wellbore, the temporary plug comprising the releasablefluid flow path indicator material. Still another feature of the deviceis that the temporary plug may comprise a dissolvable material, whereinthe dissolution of the dissolvable material releases the releasablefluid flow path indicator material.

In another embodiment, a downhole tool for forming an opening in a wallof a wellbore is disclosed. The downhole tool comprises a traceroperatively associated with a tracer release actuator, the tracerrelease actuator releasing the tracer from the downhole tool to indicateformation of an opening in a wall of a wellbore.

A further feature of the downhole tool is that the downhole tool may bea perforating charge comprising an explosive material, the tracerrelease actuator is the explosive material, and the tracer releaseactuator is actuated by ignition of the explosive material so that thetracer is released from the perforating charge to indicate formation ofthe opening in the wall of the wellbore. Another feature of the downholetool is that the tracer may be disposed within the explosive of theperforating charge. An additional feature of the downhole tool is thatthe tracer may be disposed as part of a layer disposed over theexplosive material of the perforating charge. Still another feature ofthe downhole tool is that the downhole tool may be a temporary plugdisposed in the opening in the wall of the wellbore, the temporary plugcomprising the tracer, and wherein the tracer release actuator is thetemporary plug and the tracer release actuator is actuated by removingthe temporary plug from the opening in the wall of the wellbore. Afurther feature of the downhole tool is that the tracer may be disposedwithin a dissolvable material of the temporary plug.

In an additional embodiment, an improved perforating device having acase and an explosive material disposed therein is disclosed. Theimprovement comprises at least one releasable indicator material forindicating activation of the perforating device. A further feature ofthe improved perforating device is that the releasable indicatormaterial may be disposed within the explosive material of theperforating device. Another feature of the improved perforating deviceis that the releasable indicator material may be disposed as part of alayer disposed over the explosive material of the perforating device.

In still another embodiment, an improved temporary plug for insertion inan opening in a wall of a wellbore is disclosed. The improvementcomprises a releasable indicator material for indicating removal of atleast a portion of the temporary plug. A further feature of the improvedtemporary plug is that the temporary plug may comprise a dissolvablematerial having the releasable indicator material disposed therein sothat dissolution of the dissolvable material releases the releasableindicator material thereby indicating the removal of at least a portionof the temporary plug.

In a further embodiment, a method of indicating formation of a fluidflow path in a wall of a wellbore is disclosed. The method comprises thesteps of: (a) disposing a device comprising a releasable indicatormaterial in a wellbore; (b) activating the device causing formation of afluid flow path in a wall of the wellbore and releasing the releasableindicator material from the device; (c) transporting the releasableindicator material toward a surface location of the wellbore; and (d)detecting the releasable indicator material thereby indicating to anoperator at the surface location of the wellbore that the device wasactivated and a fluid flow path was formed in the wall of the wellbore.

A further feature of the method is that the device may be activated byignition of a perforating device having an explosive material, theignition of the perforating charge causing formation of the fluid flowpath in the wall of the wellbore and releasing the releasable indicatormaterial from the device. Another feature of the method is that thedevice may be a temporary plug, the temporary plug being disposed withinan opening in the wall of the wellbore thereby restricting fluid flowthrough the opening, and wherein the temporary plug is activated bydissolving the temporary plug, the dissolution of the temporary plugcausing formation of the fluid flow path in the wall of the wellbore andreleasing the releasable indicator material from the device. Anadditional feature of the method is that the releasable indicatormaterial may be transported toward the surface location of the wellboreby fluid being circulated through the wellbore. Still another feature ofthe method is that the releasable indicator material may be transportedtoward the surface location of the wellbore by a fluid entering thewellbore through the fluid flow path.

The perforating devices, plugs, and methods for indicating hydrocarbonflow have the advantages of: providing an indication to operators at thesurface of a well that specific perforating charges have detonated;providing an indication to operators at the surface of the well as towhich perforations are contributing to flow; providing an indication tooperators at the surface of a well that a perforating charge hasdetonated; providing an indication to operators at the surface of a wellthat a temporary plug has been removed; providing an indication tooperators at the surface of the well that new hydrocarbons are beingrecovered from the formation; and/or providing an indication tooperators at the surface of the well that hydrocarbon flow from theformation through the previously plugged perforations has occurred.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of one specific embodiment of aperforating charge having tracers.

FIG. 2 is a cross-sectional schematic view of an oil well casing orconduit in a borehole having four temporary plugs, two on either side ofthe casing.

FIG. 3 is a cross-sectional schematic view of an oil well casing orconduit in a borehole having two flow paths, one on either side of thecasing, where the temporary plugs have been dissolved, disintegrated, ordegraded.

While the invention will be described in connection with the preferredembodiments, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications, and equivalents, as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF INVENTION

Referring now to FIG. 1, downhole device 20 is perforating charge 21.Perforating charge 21 has a shaped case or outer shell 22 with opening24 at a discharge end and attachment member 26 at an initiation end.Attachment member 26 facilitates placement of perforating charge 21within a perforating gun (not shown). Attachment member 26 alsofacilitates connection of perforating charge 21 to detonator cord 27,such as primer cord or other detonating cord or device known in the artto facilitate detonation of perforating charge 21.

Primer 30 is adjacent to or in communication with detonating cord 27 andwith explosive material 32. Explosive materials 32 are known to personsof ordinary skill in the art and include RDX, HMX, PYX, and HNS. Liner34 is disposed over explosive material 32 to protect explosive material32 from the environment. Due to primer 30 being in communication withdetonating cord 27 and explosive material 32, when primer 30 isdetonated by detonating cord 27, explosive material 32 is also detonatedand the explosive force is directed out of opening 24.

It is to be understood that downhole device 20 is not limited to thestructure discussed above. To the contrary, downhole device 20 may beany perforating device known to persons of ordinary skill in the art.For example, downhole device 20 may be any other type of case guncharge, shaped charge, or encapsulated charge.

As illustrated in FIG. 1, tracers 36 are disposed within explosivematerial 32. Alternatively, or in addition to, tracers 36 may beincluded within or on the surface of liner 34 or within a chamber,cavity, or other compartment or carrier that releases tracers 36 upondetonation of perforating charge 21. Each tracer 36 may be, for example,a microscopic encoded tag such as those available from MicroTracelocated at 3100 84th Lane NE, Suite A, Minneapolis, Minn. 55449-7264, acolored dye, a radio-frequency tag, a radioactive material, a florescentmaterial, or any other tracer element or device know to persons ofordinary skill in the art that can be detected in drilling fluid.

In one specific embodiment, different tracers 36 are disposed indifferent perforating charge 21 comprising a string of perforatingcharges 21, thereby providing different indications as to whichperforating charge 21 exploded and/or which perforation is the source ofthe hydrocarbon flow. For example, one perforating charge 21 may havetracer 36 that is a microscopic tag that is different from themicroscopic tag of tracer 36 disposed in a second perforating charge 21.If the operator detects only one of tracer 36, the operator candetermine, based upon his knowledge of the location of each perforatingcharge 21 and the microscopic tag tracer 36 associated with eachperforating device, which perforating charge 21 detonated and/or whichperforating charge 21 created the perforation for the flow ofhydrocarbon. Alternatively, the different tracers 36 for eachperforating charge 21 may be different from the others, i.e., oneperforating charge 21 has tracer 36 that is a colored dye, oneperforating charge 21 has tracer 36 that is a radio-frequency tag, andone perforating charge 21 has a tracer 36 that is a microscopic encodedtag.

Therefore, various combinations of the different types of tracers 36 canbe used to better educate the operator as to the location of theperforation as well as the source of the hydrocarbon flowing through theperforation. As a result, the amount or type of information imparted tothe operator by each tracer 36 can be modified as desired by theoperator.

In operation, perforating charge 21 is placed within a perforating gunand the perforating gun is included as part of a perforating string (notshown). The perforating string is lowered into the wellbore to thedesired depth and orientation. Perforating charge 21 is then detonatedto form a perforation (not shown) in the side of the wellbore and intothe well formation, generally, through the casing. Upon detonation, oneor more tracers 36 are forced out of perforating charge 21 and into theperforation and area around the perforation.

Therefore, presuming that a fluid such as oil, water, gas, or otherhydrocarbon fluid is released from the well formation tracers 36 arepicked up by the flowing fluid and carried to the surface of the well.Upon reaching the surface of the well, tracers 36 are detected by anoperator of the well, such as the operator of the perforating string, orother downhole tool string, either visually or using equipment designedspecifically for the detection of tracer 36. Identification of tracers36 by the operator provides an indication that fluid is flowing throughperforations.

Alternatively, drilling fluid or some other type of fluid may also bepresent in the wellbore, such as by circulating the fluid through thewellbore from a surface location of the wellbore, so that if fluid suchas hydrocarbon fluid or water is not released from the well formation,tracer 36 will be carried to the surface of the well to indicate thatperforating device 20 detonated.

In one specific embodiment, tracers 36 may be formed integral with theexplosive material 32 or liner 34 that forms perforating charge 21. Inother words, in these embodiments, one or more tracers 36 is embedded ordisposed within explosive material 32 or liner 34 during the formationof explosive material 32 or liner 34.

As illustrated in FIGS. 2-3, in another embodiment the downhole deviceis temporary plug 40 comprising tracers 36. As shown in FIG. 2, in thisparticular embodiment, tracers 36 are disposed within temporary plug 40.Temporary plug 40 is formed from a dissolvable material. “Dissolvable”means that the material is capable of dissolution in a fluid disposedwithin the well such as oil, gas, or drilling fluids and muds. The term“dissolvable” is understood to encompass the terms degradable anddisintegrable. Likewise, the terms “dissolved” and “dissolution” alsoare interpreted to include “degraded” and “disintegrated,” and“degradation” and “disintegration,” respectively.

The dissolvable material may be any material known to persons ofordinary skill in the art that can be dissolved, degraded, ordisintegrated over an amount of time by a temperature or fluid such aswater-based drilling fluids, hydrocarbon-based drilling fluids, ornatural gas, and that can be calibrated such that the amount of timenecessary for the dissolvable material to dissolve is known. Suitabledissolvable materials include polymers and biodegradable polymers, forexample, polylactide (“PLA”) polymer 4060D from Nature-Works™, adivision of Cargill Dow LLC; TLF-6267 polyglycolic acid (“PGA”) fromDuPont Specialty Chemicals; polycaprolactams and mixtures of PLA andPGA; solid acids, such as sulfamic acid, trichloroacetic acid, andcitric acid, held together with a wax or other suitable binder material;polyethylene homopolymers and paraffin waxes; polyalkylene oxides, suchas polyethylene oxides, and polyalkylene glycols, such as polyethyleneglycols. These polymers may be preferred in water-based drilling fluidsbecause they are slowly soluble in water.

In calibrating the rate of dissolution of the dissolvable material,generally the rate is dependent on the molecular weight of the polymers.Acceptable dissolution rates can be achieved with a molecular weightrange of 100,000 to 7,0000,000. Thus, dissolution rates for atemperature range of 50° C. to 250° C. can be designed with theappropriate molecular weight or mixture of molecular weights.

In one embodiment, the dissolvable material dissolves, degrades, ordisintegrates over a period of time ranging from 1 hour to 240 hours andover a temperature range from about 50° C. to 250° C. It is to beunderstood that both time and temperature can act together to dissolvethe dissolvable material. Additionally, water or some other chemicalcould be used alone or in combination with time and/or temperature todissolve the dissolvable material. Other fluids that may be used todissolve the dissolvable material include alcohols, mutual solvents, andfuel oils such as diesel.

It is to be understood that the dissolvable materials are consideredsuccessful if the dissolvable material disintegrates or degradessufficiently to remove a sufficient amount of temporary plug 40 torelease the tracer and permit flow through the pathway or opening withinthe wall of the wellbore. In other words, the dissolvable materials areconsidered effective even if not all of the dissolvable materialdisintegrates, degrades, dissolves or is displaced and/or not all oftemporary plug 40 across the flow pathway is removed.

In an alternative embodiment, the dissolvable material is consideredsuccessful if at least 50% of the dissolvable material disintegrates,degrades, dissolves or is displaced, and/or at least 50% of thedissolvable material across or within the flow pathway is removed. Inanother embodiment, at least 90% of the dissolvable material in the flowpathway is disintegrated, removed or otherwise displaced. Either ofthese rates of removal may be considered “substantial removal” as thatterm is used herein.

As illustrated in FIGS. 2-3, vertically oriented, cylindrical casing orwell liner 50 has opening or orifice 52 on either side thereof. Orifice52 may be created by a perforating gun, by machining prior to run-in ofthe casing to the well, or other suitable technique. Casing 50 is placedin wellbore or borehole 56 having walls 58 through a subterraneanreservoir or well formation 60. Borehole wall 58 may have filter cake 62thereon as may be deposited by a drilling fluid or, more commonly, adrill-in fluid. Filter cake deposition is a well known phenomenon in theart. If present, filter cake 62 prevents the flow of liquids and must beremoved prior to the flow of hydrocarbons from well formation 60, or theinjection of water into well formation 60. Therefore, as discussed ingreater detail below, in circumstances in which filter cake is present,temporary plug 40 and filter cake 62 must both be removed beforehydrocarbon flow can occur.

In one specific embodiment, two temporary plugs 40 define a cavity 42into which a specially sized gravel pack material 42 is disposed. Inthis embodiment, the specially sized gravel pack material 42 may alsoinclude one or more tracers 36.

Although it is expected that temporary plugs 40 are generallycylindrical in shape and have a circular cross-section, due to ease ofmanufacture, this is not a requirement of, nor critical to, temporaryplugs 40. Temporary plugs 40 are surrounded and fixed in place (but notmade permanent) by cement 70 introduced into annulus 72 of the well. Itis to be understood that cement 70 (or other suitable rigid material,e.g. a non-biodegradable polymer different from temporary plug 40) formsa pathway around each temporary plug 40 that is more evident oncetemporary plug is removed (FIG. 3, discussed in greater detail below).

Alternatively, collars, sleeves, barriers, or tubes (not shown) mayencompass temporary plugs 40 to provide additional support.

Between the states of the wells shown in FIGS. 2 and 3, temporary plugs40 are dissolved, degraded or disintegrated through a mechanism such asheat, fluid flow, the passage of a sufficient amount of time, e.g. a fewhours, or a combination thereof.

In embodiments in which a filter cake 62 is present, temporary plug 40is preferably formed out of a dissolvable material that, upondissolution, disintegration, or degradation, a product is formed, suchas an acid or other agent, that in turn removes filter cake 62 fromadjacent the former location of temporary plug 40. The resultingstructure would appear schematically similarly to FIG. 3 where flowpathways 74 are left through cement 70 between orifices 52 and wellformation 60. After this point, the well would be ready to be produced(hydrocarbons flowing through flow pathways 74 from well formation 60into casing 50), or the well would be ready to have water injected inthe direction from casing 50 through flow pathways 74 into wellformation 60.

While temporary plug 40 could be degraded by the application of aliquid, such as an acid or other chemical, it should be understood thatone difficulty with doing so is getting the liquid to distributeeffectively through the entire length of casing 50. As noted above, oneaspect of the removing temporary plug 40 and resuming hydrocarbon flowis that when temporary plugs 40 dissolve or degrade, the product islocally formed and directly delivered at many sites along the length ofborehole 56. If a liquid such as an acid or other agent is delivereddownhole to dissolve or degrade temporary plugs 40, filter cake 62 nextto temporary plugs 40 would likely also be removed and the liquid wouldbe free to leak off into well formation 60, instead of continuing downcasing 50 to subsequent temporary plugs 40.

In operation, drilling fluid or other fluid may not be present in thewellbore that could carry tracers 36 from temporary plug 40 to thesurface of the well. Presuming that oil, gas, or other hydrocarbon fluidis released from the well formation 60 through flow pathways 74, tracers36 are picked up by the flowing hydrocarbon fluid and carried to thesurface of the well. Upon reaching the surface of the well, tracers 36are detected by an operator of the well either visually or usingequipment designed specifically for the detection of tracer 36.Identification of tracers 36 by the operator provides an indication thatflow has resumed through previously plugged perforations in the well.

Alternatively, drilling fluid or some other type of fluid may also bepresent in the wellbore that, if hydrocarbon fluid or water is notreleased from the well formation, tracer 36 will be carried to thesurface of the well to indicate that temporary plug 40 dissolved andflow pathway 74 was formed; however, no fluid flowed from formation 60through flow pathway 74 and into the wellbore.

The concept of inclusion of tracers 36 in temporary plugs 40 could beadvantageously used in other applications besides the completionsembodiment discussed herein. For instance, temporary plugs havingtracers 36 may be included in downhole tools to provide an indication tothe operator that the downhole tool as actuated. For example, indownhole tools such as setting tools that use drilling fluid pressure toset the tool, upon setting the tool, temporary plug 40 may be placed incontact with the drilling fluid, thereby causing temporary plug 40 todissolve or disintegrate, thereby releasing tracers 36 into the drillingfluid. The drilling fluid then carries tracers 36 to the surface of thewell for detection in the same manner as discussed above.

It is to be understood that the invention is not limited to the exactdetails of construction, operation, exact materials, or embodimentsshown and described, as modifications and equivalents will be apparentto one skilled in the art. For example, the tracers may be included inany perforating device, such as bullet perforating charges, abrasivejetting perforating devices, or as part of high pressure fluid jettingdevices, in addition to the shaped charged discussed herein.Additionally, as discussed above, the mechanism for dissolvingdissolvable material could include, but is not necessarily limited to,heat, time, contacting with drilling fluid, contacting with water orsome other chemical agent. Moreover, the dissolvable materials withtracers could be used to control the release of chemicals or activate adownhole switch such as upon the influx of water into the productionstream and to indicate that such downhole switch has been activated. Thedissolvable materials with tracers also could be used to place temporaryplugs into orifices that stay closed until water (or other agent)dissolves or degrades them and the tracers are released to indicate thatthe orifices are opened. An example might be a tool wear indicator wherethe dissolvable material and tracer are located within a closed orifice.Once worn through, the wellbore fluids dissolve the material and releasethe tracer for detection at the surface. Further, downhole hydrauliccircuits could also be constructed for “intelligent” well completionpurposes. In general, the dissolvable materials with tracers could beapplied to any situation where isolation from well fluids is desireduntil a known or predetermined event occurs to remove them and in whichconfirmation of the removal of the dissolvable material is desired.Accordingly, the invention is therefore to be limited only by the scopeof the appended claims.

1. A perforating charge having an explosive material for forming a fluid flow path in a wall of a wellbore, the perforating charge comprising: a releasable indicator material, the releasable fluid flow path indicator material being releasable from the perforating charge to indicate formation of a fluid flow path in a wall of a wellbore.
 2. The perforating charge of claim 1, wherein the releasable fluid flow path indicator material is disposed within the explosive material.
 3. The perforating charge of claim 1, further comprising a protective layer disposed over the explosive material, the protective layer comprising the releasable fluid flow path indicator material.
 4. (canceled)
 5. (canceled)
 6. A downhole tool for forming an opening in a wall of a wellbore, the downhole tool comprising: a tracer operatively associated with a tracer release actuator, the tracer release actuator releasing the tracer from the downhole tool to indicate formation of an opening in a wall of a wellbore, wherein the downhole tool is a perforating charge comprising an explosive material, the tracer release actuator is the explosive material, and the tracer release actuator is actuated by ignition of the explosive material so that the tracer is released from the perforating charge to indicate formation of the opening in the wall of the wellbore.
 7. (canceled)
 8. The downhole tool of claim 6, wherein the tracer is disposed within the explosive of the perforating charge.
 9. The downhole tool of claim 6, wherein the tracer is disposed as part of a layer disposed over the explosive material of the perforating charge.
 10. (canceled)
 11. (canceled)
 12. An improved perforating device having a case and an explosive material disposed therein, the improvement comprising at least one releasable indicator material for indicating activation of the perforating device.
 13. The improved perforating device of claim 12, wherein the releasable indicator material is disposed within the explosive material of the perforating device.
 14. The improved perforating device of claim 12, wherein the releasable indicator material is disposed as part of a layer disposed over the explosive material of the perforating device.
 15. (canceled)
 16. (canceled)
 17. A method of indicating formation of a fluid flow path in a wall of a wellbore, the method comprising the steps of: (a) disposing a device comprising a releasable indicator material in a wellbore; (b) activating the device causing formation of a fluid flow path in a wall of the wellbore and releasing the releasable indicator material from the device; (c) transporting the releasable indicator material toward a surface location of the wellbore; and (d) detecting the releasable indicator material thereby indicating to an operator at the surface location of the wellbore that the device was activated and a fluid flow path was formed in the wall of the wellbore, wherein the device is activated by ignition of a perforating device having an explosive material, the ignition of the perforating charge causing formation of the fluid flow path in the wall of the wellbore and releasing the releasable indicator material from the device.
 18. (canceled)
 19. (canceled)
 20. The method of claim 17, wherein the releasable indicator material is transported toward the surface location of the wellbore by fluid being circulated through the wellbore.
 21. The method of claim 17, wherein the releasable indicator material is transported toward the surface location of the wellbore by a fluid entering the wellbore through the fluid flow path. 